1. Technical Field
The present disclosure relates to a reciprocating compressor and a hydrogen supply system.
2. Description of the Related Art
Conventionally known machines for compressing gas include reciprocating compressors. For example, a reciprocating compressor including a cylinder, a piston, an intake valve, and a release valve is known.
As shown in FIG. 5A, Japanese Unexamined Patent Application Publication No. 2014-214695 discloses a reciprocating compressor 300. The reciprocating compressor 300 includes a cylinder 304, a piston 312, an intake valve 306a, a release valve 306b, a crank mechanism 308, a plurality of piston rings 314, oil packing 318, and rod packing 321. The reciprocating compressor 300 is used to compress hydrogen gas to an ultrahigh pressure. The piston ring 314 is made of an elastic material, and is fit on the piston 312. In a state in which the piston rings 314 are fit on the piston 312 and are inserted inside the cylinder 304, outer peripheral portions of the piston rings 314 are sliding contact with an inner peripheral surface of the cylinder 304. With this configuration, the piston rings 314 prevent gas compressed to an ultrahigh pressure by the piston 312 from leaking out from a compression chamber through a gap between the inner peripheral surface of the cylinder 304 and an outer peripheral surface of the piston 312. The piston 312 is inserted to extend through the rod packing 321 while the piston 312 is slidable in an axial direction of the piston 312. The rod packing 321 prevents gas from leaking out from the cylinder 304.
As shown in FIG. 5B, Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2012-526940 discloses a compressor 500. The compressor 500 includes a cylinder 501, a hydraulic piston 504, a piston dummy 505, a suction valve 506, and a delivery valve 507. The compressor 500 is used for the purpose of, for example, compressing a gaseous medium, such as hydrogen and natural gas. A piston chamber 502 is constituted inside the cylinder 501, and a liquid 503 is arranged inside the piston chamber 502. The liquid 503 is preferably an ionic liquid. The piston dummy 505 is arranged in the liquid 503, and the liquid 503 circulates around the piston dummy 505. During a compression stroke, the liquid 503 is moved upward together with the piston dummy 505. The contour of the piston dummy 505 is matched to the shape of a head region of a space inside the cylinder 501. For this reason, when the piston dummy 505 approaches a top dead center, the piston dummy 505 and the piston chamber 502 form a ring gap 508, and acceleration of the liquid 503 is achieved in the ring gap 508. The acceleration of the liquid 503 allows the liquid 503 to be in contact with a cylinder head to be cooled for a long time. Additionally, since the liquid 503 is accelerated in the ring gap 508, a turbulent flow is produced in the liquid 503, and the turbulent flow brings about a cooling effect.